The conventional toilet tank flushing mechanism discharges substantially the entire volume of water stored in the tank, even though only a portion of that amount may be adequate in at least certain circumstances. This, of course, wastes water and imposes an unnecessary load upon the sewerage system. While devices for selectively achieving the discharge of only a portion of the water contained in the toilet tank have heretofore been proposed, they are generally found to be deficient in one or more respects.
The three configurations of valve assemblies that are perhaps most commonly utilized in the standard toilet ar described in the prior art. One configuration that is in rather widespread use is disclosed in Harrison U.S. Letters Pat. No. 4,067,074, which utilizes a gravity tube/flush valve float assembly to control the discharge of water from the tank. Another commonly employed valve assembly is shown in Cass U.S. Letters Pat. No. 4,038,707, which utilizes a vertically sliding ball valve for flow control. A somewhat similar mechanism, commonly called a "flapper" assembly, is shown in Goldman et al U.S. Letters Pat. No. 4,225,987, and employs a ball valve closure that is pivotably mounted adjacent the discharge opening.
In order to achieve a partial flush operation, many of the prior art devices designed for that purpose employ means to interrupt movement of the closure in a position that is less than fully displaced from the valve seat, as compared to the fully open position that is attained during the normal flush. This can, however, result in spurious operation, due to the failure of the closure to be removed completely from the vortex effect, causing the closure to be drawn prematurely into the valve seat and thereby terminating flow before an adequate amount of water has been discharged. Valve assemblies of the type shown in the above-identified Goldman et al patent appear to be particularly susceptible to malfunctions of this nature.
Other systems provide a partial flush mode as the norm, and are therefore found to be unsatisfactory from a conceptual standpoint, in that they demand that the user deviate from his accustomed action in order to produce the normally expected (full flush) result. This then requires that the operator be aware of the existance and operational peculiarities of the novel mechanism, and is problematical from that standpoint. Harrison, for example, requires that the handle of the flushing mechanism be pressed inwardly to obtain the normal volume discharge; a reduced flow (and hence, in many instances, an inadequate effect) would frequently be produced accidentally by a person who is ignorant of the proper manner of operating the system, or by young children and others of limited capacity.
Accordingly, it is an object of the present invention to provide a novel flush control device, and a toilet tank flushing system utilizing the same, that permits selective operation to provide either a full or a partial flush operating mode.
It is also an object of the invention to provide such a device and system which is fully compatible with a variety of flush valve assemblies of standard design, and which requires a minimum number of parts for installation and adaptation of the system.
It is another, more specific object of the invention to provide a flush control device that produces the normal, full volume discharge upon rotation of the operating handle in the customary manner, with extraordinary measures being required to initiate the partial flush cycle.
Yet another object of the invention is to provide such a device which is easily and conveniently retrofit with existing equipment.
A further object is to provide a flush control device that functions in a desirable manner, and that does not operate by preventing the valve closure from attaining a position that is fully displaced from the valve seat.
A still further object of the invention is to provide a novel device and system having the foregoing features and advantages, which are relatively economical to manufacture, durable, effective, and facile to install and to use.